Risk analysis of an urban environment under explosive attacks in Tehran

  Purpose: In recent years high explosive bomb attacks have been increasingly directed against   civil structures by various terrorist organizations. This paper describes a numerical method for   assessing the interaction of high explosive air blast within the complex geometrical type of a   congested urban environment.   Materials and Methods: The first step in predicting blast effects on a target is to predict   blast loads on it. In this study a computational   fluid dynamics program and analytical methods   developed by the Federal Emergency Management Agency (FEMA) were used to solve two   and three dimensional air blast problems.   Results: Explosions in confined spaces (mines, buildings, large vehicles) which cause structural   collapse are associated with greater morbidity and mortality. The reflected pressures for explosive   detonations are two to thirteen times greater than peak incident pressures. A rough estimate   of the total casualties following such events are the result of the composition and amount of   involved materials, surrounding environment, delivery method, distance between the victim   and the blast, crowd density and any intervening protective barriers or environmental hazards.   Conclusion: The extent and severity of damage and injuries in an explosive event cannot be   predicted with perfect certainty. Despite these uncertainties, it is possible to give some general   indications of the overall level of damage and injuries to be expected in an explosive event based   on the size of the explosion, distance from the event and assumptions   about the construction   of the building.  blast wave risk analysis lethality assessment urban environment Ansys-cfx.